A highly active zinc catalyst for the controlled polymerization of lactide

Area of Science:

• Coordination Chemistry
• Polymer Science
• Catalysis

Background:

• Metal alkoxide complexes are crucial catalysts for cyclic ester polymerization.
• Understanding the structure-activity relationship is key to developing efficient catalysts.
• Lactide polymerization is important for producing biodegradable polymers.

Purpose of the Study:

• To synthesize and characterize a new Zn(II) alkoxide complex.
• To investigate its efficacy in lactide polymerization.
• To elucidate the polymerization mechanism and kinetics.

Main Methods:

• X-ray crystallography for solid-state structure determination.
• Nuclear magnetic resonance (NMR) and mass spectrometry for solution-state analysis.
• Lactide polymerization experiments with detailed kinetic studies.

Main Results:

• The Zn(II) complex exists as a dimer in solid-state but monomer in solution.
• Efficient polymerization of lactide with good molecular weight control (up to 130 kg mol(-1)).
• Established the rate law and demonstrated faster polymerization rates than other zinc systems.

Conclusions:

• The monomeric L(1)ZnOEt is an active catalyst for lactide polymerization.
• The catalyst provides high molecular weight polylactide with narrow distribution.
• This study offers valuable mechanistic insights into metal-catalyzed cyclic ester polymerization.